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Institute of Astronomy PUBLIC OPEN EVENING — 18 February 2015 — I really don’t know clouds at all: Mars’ giant plumes still a mystery PAST observations of strange plumes of material on Mars are proving a problem to explain. In March and April 2012, amateur astronomers reported observing a towering plume of gas stretching up to altitudes over 250 km, well into the thin upper reaches of the Martian atmosphere. Each time the plume took less than 10 hours to develop, and then persisted for about 10 days before fading away. Both plumes occurred above the same region of the Martian surface; what they are and how they were caused remain ambiguous. One explanation is that they are simply large reﬂective clouds of wateror carbon dioxide-ice mixed with dust particles. However, this does not ﬁt with previous observations of cloud features that remain below 100 km. Alternatively, the plumes could be some kind of aurora (i.e. Martian “Northern Lights”) caused by anomalies in the surface magnetic ﬁeld. Although auroral lights have been observed before in this spot, they have always been a thousand times fainter. So the mystery remains—perhaps until a canny amateur is able to catch the next plume forming. outreach A TONIGHT’S SPEAKERS Zephyr Penoyre & The CHaOS Crew Building a universe in a year Our weekly welcome W The March 2012 sighting of a mysterious high-altitude plume on Mars (circled) and its evolution. Image: W. Jaeschke & D. Parker 18 new odd-couple stars with age, mass gap ASTRONOMERS have discovered very mismatched binary stars, where one star is shining while the other has yet to ﬁnish forming. The Sun is unusual in being a singleton, as most stars are born in pairs. The majority of such “binary” stellar systems comprise companions of equal mass, but maybe that is not always the case. Mismatched pairs are hard to ﬁnd—a very massive star will easily outshine a smaller companion and hide its presence. The 18 newly discovered systems were only identiﬁed by the way the smaller star moved between us and its massive companion, blocking some of the latter’s light to cause a slight eclipse. The stars in the new systems exhibit extreme diﬀerences in mass (the heavier star weighs in at 6–16 solar masses, with its partner at 1–2 solar masses), and circle each other very tightly with orbits lasting only 3–9 days. Even stranger, anomalies in the signal of the eclipse show that the fainter and less massive object is not yet a fully formed star. The more massive star has somehow formed while the other is still contracting under gravity. The excitement of discovering such systems lies in the way they may tell us how massive stars in binaries can form and evolve. HAT if the Universe were built in just one year? Allow the CHaOS Science Roadshow to illustrate with hands-on demonstrations, plenty of crashes and explosions, and one very large clock. This special presentation begins as usual at 7.15pm, and will be followed by an opportunity to observe if (and only if…) the weather is clear. The IoA’s historical Northumberland and Thorrowgood telescopes will be open for unaided-eye observations, and we will be staﬃng some smaller telescopes around the observatory lawns. The Cambridge Astronomical Association will also provide an outdoors ﬂoorshow relaying live images from three modern telescopes, with commentary. If we’re unlucky and it’s cloudy, then we’ll oﬀer you a cup of tea as compensation, and the CAA will oﬀer some more astro-information afterwards in the lecture theatre for those who want to stay on. We tweet current astro-news and events as IoACOA. Please e-mail any questions, comments or suggestions about the IoA Public Open Evenings to Carolin Crawford at [email protected] www.ast.cam.ac.uk/public WHAT YOU CAN LOOK FORWARD TO: ⊕ A series of half-hour astro-talks in our lecture theatre � Posters, displays, demonstrations and activities all around the site, for everyone to learn more about astronomy and the kind of research we do ⊕ Our librarian Mark will showcase some of the rare and unique astro-gems to be found in our historical library � If you’re a Dr Who fan, then come along and meet the 15th Cyber Legion ⊕ The Cambridge Science Centre will bring along some of their hands-on displays from their forthcoming Explore the Universe exhibition � Meteorites to examine and purchase from our friends at Spacerocks UK ⊕ A glass art exhibition in one of the telescope domes � Visit the historical telescopes on site and see what they look like in daylight ⊕ Our Starlite cafe will provide tea and snacks, as well as a chance to rest your feet � The CAA will oﬀer family make-and-do activities, and showcase a range of amateur telescopes Please note that this year we are not oﬀering observing in the evening Other astro-events to put in your diary 20 MAR: SOLAR ECLIPSE VIEWING 20 FEB: GAIA MISSION UPDATE The IoA’s Heather Campbell will give an update on the Gaia satellite mission this Friday 20th February. The talk will be held in the Sackler Lecture Theatre at the IoA, and starts at 8pm. Everyone is welcome. 16–21 MAR: GLASS ART EXHIBITION Glass artist Livvy Fink will be exhibiting some of her artwork (right) at the IoA on 16th–21st March. These pieces were inspired by an ongoing collaboration between the IoA and Cancer Research UK; they explore the relationship between macro-structures and micro-structures, and the sense of wonder they both provoke. The artwork captures impressions of unfamiliar worlds inspired by the most distant galaxies and the cells within us, where light is diﬀused through a myriad of intricate surfaces suspended within glass. The IoA and CAA are combining forces to celebrate the solar eclipse occurring on the morning of Friday 20th March. A solar eclipse occurs when the Moon passes between us and the Sun, casting a shadow on the Earth’s surface. From Cambridge the eclipse will be partial, but at maximum coverage the Moon will obscure a whopping 85% of the Sun. This is the only chance to see a major eclipse here for several years. The eclipse will last from 8.26am to 10.43am. We shall provide a series of short talks at the IoA, and hope to relay a live feed from locations where the event will appear as a total eclipse. If the weather is clear, we will also open up the telescopes at the Observatory for safe viewing of the eclipse.